The former New Mexico governor cast himself as a fiscal conservative and a social liberal dismayed by the size of government. "Government is too big. It's unwieldy," he said during an interview with Neil Cavuto on Fox Business. "It's out of control. We need to get control."

Johnson, a self-made millionaire, has served as president and CEO of Cannabis Sativa, a Nevada-based marijuana marketing and distribution company. He received nearly 1.3 million votes in his 2012 bid — far behind the major nominees but the best showing for a Libertarian candidate.

Johnson, a former Republican, still has to secure the support of Libertarians at the party's convention later this year.